| Abstract
| - Solvent effects on helicity induction in zinc bilinone (ZnBL) derivatives bearing chiral auxiliariesat their 19-positions were investigated by using circular dichroic spectroscopy and 1H NMRexperiments. In ZnBLs 1 and 2, which possess (R)-2-methyl-1-phenylpropyloxy and (R)-1-phenylethyloxy groups at their 19-positions, respectively, the efficiency of helicity induction wassignificantly affected by employed solvents (78−95% de in 1 and 33−89% de in 2). The free energychanges of the P−M interconversion of 1 and 2 were linearly in proportion to reduction inpolarizability of solvents: lower polarizability of solvents led to better efficiency of helicity inductionin 1 and 2. With the support of the 1H NMR study in addition to the molecular modeling previouslyreported, it was indicated that the solvophobic van der Waals interaction between the alkyl groupin the chiral auxiliary and the A-ring of the bilinone skeleton in the preferred conformer plays acrucial role in determining the efficiency of helicity induction in 1 and 2.
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